1. Field of the Invention
This invention relates to a sleeve for holding a cutting bit and a block for holding a cutting bit. More particularly, this invention relates to a sleeve for holding a cutting bit and a block for holding a cutting bit in which either or both of the sleeve and the block has a flange with an undercut portion to ease removal of the sleeve and block.
2. Description of the Prior Art
Press fit or shrink fit sleeves in holding blocks for cutting bits have been common in the mining and construction industries for many years. However, one difficulty with these sleeves occurs when the sleeve is damaged or worn out and must be removed from the holding block. One method for removing such a sleeve involves cutting the sleeve out with a torch. A second method for removing the sleeve involves the use of a hydraulic cylinder and pressure device which physically forces the sleeve from the holding block. Both of these methods are slow and require extra equipment. Furthermore, both of these methods require an operator with training and experience.
U.S. Pat. No. 5,374,111, entitled "Extraction Undercut For Flange Pits" and assigned to Kennametal Inc., the assignee of the current application, addresses the use of a rotatable cutting bit, not a sleeve or holding block, having a flange with an undercut whereby the undercut may be employed in removing the rotatable cutting bit from a holder. Extracting cutting tools from holders has been a longstanding problem and it has been relatively common to employ some sort of a pulling device to physically remove a cutting bit from a holder.
However, the inventors of the subject application have realized the need for easier removal of sleeves from holding blocks.
In a related matter, the block utilized to secure a cutting bit, whether with or without an intermediate sleeve, is itself secured to a rotary tool, such as a longwall miner rotary drum, by welding it to the drum. While this provides a very secure attachment to the drum, in the event the block became damaged it is necessary then to utilize a torch to cut out the block from the drum and to replace it with a functional block. This method is also slow and requires extra equipment. Furthermore and once again, this method requires the operator to be trained and experienced. Therefore, a design is sought for the block which holds the cutting bit to promote relatively easy removal and replacement of the block in the event it becomes damaged or worn. The inventors of the subject application, therefore, have also realized the need for easier removal of the block from a holder.